1. Field of the Invention
An apparatus consistent with the present invention relates to a magneto resistive (MR) head having a magneto resistive (MR) element.
2. Description of the Related Art
Recently, the recording density of magnetic tapes has been increased. In order to follow this trend, magneto resistive (MR) heads have necessarily been used as heads for reading magnetic signals in tape drives (e.g. magnetic recording/reproducing apparatuses), instead of conventional inductive heads. An MR head has a magneto resistive (MR) element which possesses a high sensing sensitivity to magnetic signals and enables a high reproducing output. Therefore, use of an MR head makes it possible to narrow the recording tracks on a magnetic tape and to increase the line recording density of a magnetic tape, thereby realizing the high density recording and reproduction.
MR heads, however, have a property of being sensitive to static electricity and heat, in comparison with conventional inductive heads. Concretely, if an electrostatically charged magnetic tape approaches an MR head or comes into contact with it, then the static electricity is discharged through the MR head. As a result, the MR head may be damaged due to the electro-static discharge (ESD).
To overcome this disadvantage, the following conventional technique has been employed (see Japanese Unexamined Patent Application Publication 2003-123215). In this technique, an MR head has a structure that an MR element is sandwiched between magnetic shield layers and between insulating layers. Further, a substrate and a protective substrate, which are formed on the respective sides of the MR element, are both grounded. If an electrostatically charged magnetic tape comes into contact with this MR head, then the static electricity is discharged through the substrate and the protective substrate, instead of the MR element. As a result, the MR head is prevented from being damaged.
Even in this MR head, however, static electricity on a magnetic tape is not always discharged sufficiently through the substrate and the protective substrate, and the static electricity may be discharged through the MR element or charge an insulating layer formed near the MR element. In this case, the MR element is possibly damaged.
Taking the above disadvantage into account, the present invention has been conceived. An object of the present invention is to provide an MR head in which the MR element resists damage due to ESD.